Tag Archives: Stagonospora cirsii

171-175 E.L. Gasich and A.O. Berestetskiy
Studies on soil application of Stagonospora cirsii, a candidate for biological control of Cirsium arvense
Abstract |

Studies on soil application of Stagonospora cirsii, a candidate for biological control of Cirsium arvense

E.L. Gasich and A.O. Berestetskiy

All-Russian Institute of Plant Protection RAS, shosse Podbelskogo 3, 196608 Pushkin,St.-Petersburg, Russia; e-mail: elena_gasich@mail.ru

Abstract:

Stagonospora cirsii, a causal agent of Canada thistle (Cirsium arvense) leaf spot, is under development as a biological control agent for this perennial noxious weed. S. cirsii had impact as a foliar spray and it proved highly pathogenic if applied at soil surface. Since Canada thistle is a perennial weed with a very vigorous root system, the ability of fungus to survive in soil and infect roots would greatly improve its potential as a mycoherbicide. Research was conducted to study the S. cirsii population dynamics in sterile soil, on the possibility of infecting Canada thistle creeping roots ed with the fungus, and its ablity to survive after being incorporated into/on the soil after over-wintering. The population dynamic was studied by dilution technique. In our experiments we used 10 g and 400 g of sterile field sod-podsol soil. At two initial inoculation concentrations about 103 and 106 conidia g-1 of soil the CFU amount in 1 g soil gradually were stabilized at a level about 105 g-1 of soil. The population density on this level was stable for 6 months. Inoculation of the creeping roots at different stages of their development (creeping roots with buds/rosettes/young roots) in laboratory conditions showed that fungus can infect leaves only in rosettes. It seems, under natural conditions, infection of Canada thistle root system with S. cirsii is not possible. However, S. cirsii maintains viability under various conditions of over-wintering (above/under/on ground).

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